The following application proposes to study the development of the nervous system in Drosphila melanogaster. The major objectives are to generate a behavioral substitute for histochemical markers of nervous system genotype, to complete a fate mapping of the lateral nervous system, to carry out an autoradiographic analysis of the histogenesis of larval and adult nervous systems to assay for the existence of developmental compartments in the nervous system by the use of various genetic mosaics, characterize particular mutants which seem to effect synapse formation between eye and brain, and to characterize the interactions in space and time which lead to normal or abnormal eye-brain wiring.